Automatic electric fire-alarm signal.



No. 880,662. PATENTED MAR. 3, 1908. E. 3. HAYDEN.

AUTOMATIC ELECTRIC FIRE ALARM SIGNAL.

APPLICATION FILED MAYII. 190s. RENEWED JULY 2, 1907.

31mm EEHH YDEN,

EDWARD EVERETT HAYDEN, OF WASHINGTON, DISTRICT OF COLUMBIA.

AUTOMATIC ELECTRIC FIRE-ALARM SIGNAL.

Specification of Letters Patent.

Patented March 3, 1908.

Application filed May 11. 1906. Serial No. 316.363- Renewed July 2. 1907. Serial No. 881.925.

appertains to make and use the same.

My invention relates to improvements in automatic electric fire alarm signals, and the object of my invention is to produce a simple device of this type, which under ordinary circumstances may be used just like the common electric push button, but which when heated, automatically closes the circuit giving an alarm.

With this object in view my invention consists in the construction and combination of parts as hereinafter described and claimed.

In the accompanying drawings Figure 1 is a face view of my complete device; Fig. 2 is a similar view with the outer casing removed, and the outercontact armbroken away to show the inner contact arm; Fig. 3 is a side view of the device under ordinary circum-. stances, the outer casing being removed; Fig. 4 is a similar view showing thesame expanded under the influence of heat, the outer contact arm being shown in dotted lines; Fig. 5 is an enlarged perspective View of the inner contact arm in its ordinary condition; and Fig. 6 is a longitudinal section of the device'with the cover and push button removed.

a represents the backing, b the removable. front casing, c the push button, cl and e the circuit wires, and j the outer contact arm made in the form of a short spiral spring, all of these parts being of the usual construction. The outer casing b/is adapted to screw u on the backing, screw threads 9 being provided for that purpose.

In the device shown in Fi 3, the s ring f is shown further away from t e point h than would be the normal position when the button 0 is in place. The inner contact arm h, as shown in Fig. 2, is preferably made in a spiral form, so that in a small space conslderable length of arm may be secured, and a correspondin increase of the bend or outward motion 0 the free end is secured when heated. This inner contact arm h consists of two metal strips of different co-eliicients of expansion brazed or otherwise secured together, the upper strip i being made preferably of steel, and the lower strip of brass or other material having a higher co-' ellicient of expansion than steel. A screw is is used to secure the contact h to the backing.

It will be obvious that under ordinary circumstances pushing on the button 0 will cause the arm f to contact with the point if, and thus the device may be used as an ordinary push button, while when it is subjected to a considerable degree of heat the brass on the inner contact arm expands more rapidly than the steel, bending the arm outwards and causing the point h to make electrical con-.

tactwith the armf, as shown in Fig. 4. The

bend or expansion of the arm h is shown as exaggerated in Fig. 4,, for the sake of clearness in the drawings.

It is preferable to have the inner contact arm h as the one to bend under the influence of heat because this arm is not acted upon by the push button, and furthermore, is next the wall orelevator shaft, and thus is more apt to get heated than the outer arm which is next the wood case (1. But it will be evident that the outer spring may also be made of two metals, superimposed but in low tern eratures, the socket is cut away or' indente to allow for such bending, as shown at m, Fig. 6.

It will be obvious that the circuit will continue to be closed as long as the spiralis maintained at the high temperature, but when the temperature falls again, as by uttingout the fire, the circuit will be broken, and the bell will stop ringing.

Having thus described my invention, what I claim and desire to secure by Letters Patent of the United States, is v r In an automatic'electric fire alarm signal, the combination of 'a backing having a central hollowed out portion, a casing carrying a push button and adapted to be secured upon said backing, a contact member consisting of strips brassand steel fastened together curved into the form of a spiral and In testimon whereof, I aflix my signature,

normally contained said hollowed out in presence 0 two witnesses. portion, and a reslhent contact member adapted to be lgushed in by said push button, EDWARD EVERETT HAYDENT 5 or to be struc by said first named contact Witnesses:

member as it ex ands under the influence of A. L; HOUGH,

heat, substantia 1y as described. J. STEPHEN GIUsTAf 

